Electric heater



Nov. 11, 1941. E. N. LIGHTFOOT ELECTRIC HEATER Filed Oct. 2, 1939 am? an BAgl za an 2 Sheets-Sheet l 1941- E. N. LIGHTFOOT 2,262,507

ELECTRIC HEATER Filed Oct. 2, 1939 2 Sheets-Sheet 2 Patented Nov. 11, 1941 ELECTRIC HEATER Edwin N. Lightfoot, Wauwatosa, Wis., assignor to Cutler-Hammer, Ina,

poration of Delaware Milwaukee, Wis., a cor- Application October 2, 1939, Serial No. 297,499 Claims. (Cl. 219-37) This invention relates to improvements in electric heaters, and the invention relates more particularly to electric heaters of the range top type.

An object of the invention is to generally improve the details of construction and arrangement of the parts of such heaters whereby the utility and efficiency thereof is increased, and whereby such increased efliciency may readily be maintained.

Another object is to provide a unit comprising one or more spirally coiled heating elements of the tubular or sheathed type.

Another object is to provide a concentric arrangement of a plurality of inner and outer coiled heating elements whereby a greater number of heating effects may be produced thereby.

Another object is to provide novel supporting means for the heating element or elements.

Another object is to provide a drip and reflector pan of novel form which may be very readily removed for cleaning and polishing thereof for the purpose of sanitation and for maintaining the desired efficiency of the heating element.

Another object is to so of the heater element or elements at one side of the opening in the range top as to provide for protection thereof and of the circuit wires connected thereto.

Other objects and advantages of the invention. will hereinafter appear.

The accompanying drawings illustrate a preferred embodiment of my invention, and modifications of certain structural details thereof,

arrange the terminals which will now be described; it being understood that the device illustrated is susceptible of change in respect of other structural details thereof within the scope of the appended claims.

In the drawings, Figure I is a top plan view of an electric range top heater and the supporting and reflecting elements associated therewith, a fragment of the range top being shown to illustrate the notched form of the opening therein.

Fig. 2 is a view partly in side elevation and partly in vertical section on the line 2-2 of Fig. 1, and showing the manner in which the reflector pan may be tilted to facilitate removal thereof.

Fig. 3 is a vertical sectional view, on the line parts of the heating elements elevation, and parts thereof the various elements of the the normal positions there- 3-3 of Fig. 1, being shown in side being broken away, device being shown in of when in use.

Fig. 4 is a bottom plan view of the device shown in Figs. 1 to 3, the range top plate being omitted to better illustrate certain structural details of the device.

Fig. 5 is a fragmentary view, partly in side elevation and partly in vertical section, illustrating certain coils of one of the tubular heater elements and the manner in which the same are interlocked with the frame comprising a plurality of plates arranged on edge.

Fig. is a fragmentary vertical sectional view illustrating a modified form of support for the frame and its associated tubular heater coils, this arrangement providing for elimination of the rim or ring, or for use of a rim or ring unattached to the support for the heating unit, and

Fig. 7 is a fragmentary view quite similar to Fig. 5, but with a different form of notches for interlocking engagement with the tubular heater coils.

Referring first to the device illustrated in Figs. 1 to 5, the numeral I5 designates a range top, which may be formed of sheet metal, such as stainless steel, or of ordinary sheet steel having its outer surface provided with a coating or covering of vitreous enamel to facilitate cleaning or polishing of the range top. The range top is provided with one or more substantially cir cular openings 16, the number of openings and the size thereof being varied in accordance with the number and size of the heating units to be associated with the range top. Opening i6 is preferably provided with four equally spaced peripheral notches H which are adapted for interlocking engagement with parts of the unit supporting means to prevent relative rotary displacement between the same and the range top.

The supporting means for the heater unit preferably comprises a steel ring or rim I8 having a relatively short downwardly extending outer peripheral flange l9 (Fig. 2) the edge of which is adapted to seat against the outer surface of the range top plate l5, and a relatively longer downwardly extending inner peripheral flange 20 which freely penetrates the opening L6 in said top plate but is engageable with any portion of the wall of said opening to prevent substantial lateral displacement of the rim. The outer surface of rim l8, including the outer or exposed surfaces of flanges I9 and 20, is preferably plated with chromium or similar material, which plated surface is highly polished. A pair of strip metal members 2| and 22 are arranged to cross each other flatwise at right angles at a point concentric with the rim I8, and said members have their opposite flanged ends (see 2|, 2|, Fig. 3)

rigidly secured to the inner surface of the rim flange 28 and/or to the inner horizontal surface of the rim I. as by welding. The intermediate horizontal portions of members 2| and 22 are offset downwardly a. substantial distance below the plane of top plate l5, and the same are provided at opposite ends of the respective intermediate portions with upwardly offset horizontal portions 2|, 2| and 22, 22. Said last mentioned horizontal portions provide a seat for the peripheral flange 23 of a reflector pan 23 which is of slightly dished or concave form as bestopenings in an insulating terminal block 30, said end portions being provided with suitable terminal posts 21, 21, 28 and 28 respectively, which are accessible from the outer face of block 38. Terminal posts 21 and 28 are electrically connected to terminal members 3| and 32, re-

' a binding screw, accessible from the outer face Welded or otherwise rigidly attached to the outer surfaces of the vertical portions 2|, 2|

, and 22, 22 of members 2| and 22 are four like members 24, each of which has a pair of inwardly extending parallel lugs 24' and 24, between each pair of which one of the four supporting feet or ends of a frame member is adapted to rest or seat against the respective portions 2|, 2|

22, 22 aforementioned (see Figs. 1 and 3).

Said frame member preferablyv comprises a pair of sheet metal elements 25, 26 of similar form, said elements being bent at points slightly offset from the mid-lengths thereof, respectively, to provide pairs of arms 25, 25 and 26, 2|; extending at substantially right angles to each other (Fig. l). Arms 25, 26 have sheared and bent therefrom, to lie in the planes of their respective integrally connected arms 25 and 26 lugs 25 and 26. The arms 25, 25 and 26', 26 have their lower edges cut away to a predetermined degree except at the outer ends thereof which provide feet 25, 25 and 26, 26 for engagement with the aforementioned horizontal portions 2|, 2| and 22, 22 (Figs. 1, 2 and 3). Said cut away portions of am 25'', 25 and 26*, 2|i' thus provide clearance for the flange 23* of pan 23.

The upper edges of the respective arms are suitably notched, in the manner best illustrated in Figs. 1 and5; to accommodate the concentrically arranged outer and inner sets of spirally wound coils 21 and 28, respectively, of the tubular heater elements. The notches are formed as shown in detail at 28 in Fig. 5, the same being arranged to support all coils of the respective sets with the upper surfaces thereof in a common plane, slightly above "the upper edges of said the notches 23 is substantially vertical and the outer side wall thereof, is curved inwardly adjacent to the open end of said notch, to provide a. sort of hook formation on the latter, to accommodate the correspondingly shaped transverse contour of the heating element in the normal position ofthe latter when assembled.

The end portions 21 and 21 of the outer set of coils 21 and the end portions 28 and 28 of the inner set of coils 28 are offset downwardly in a plane below that of said sets of coils and are arranged to just clear the upper surface of the peripheral flange 23 of reflector pan 23, as best shown in Fig. 2. End portions 21, 21 28 and 28 are brought together-at one side of the heater unit where they penetrate spaced arms. As shown, the inner side wall of each of an integral peripheral of said block, to provide for connection of said heater elements to a source of electric current supply through the medium of any suitable switching means to provide for heat control or regulation.

End portions 21*, 21", 28 and 2|! are rigidly clamped between the two suitably formed sheet metal members 35 and 36 comprising a clamping device which abuts the inner face of terminal block 30. Clamping members 35 and 36 are secured to each other by screws 31, 31 and 31, the latter being also preferably employed to secure a wire to said clamping device whereby to provide for connection of the sheaths of said heater elements to a suitable ground.

Terminal block 38 and thus .the aforementioned terminals are arranged beneath range top |5 at one side of the opening l6 therein and so are protected from dripping, boiling over or spilling of the contents of utensils which are set upon the heating elements or the range top. The aforedescribed arrangement of the terminals andsaid end portions permits use of a drip and reflector pan 23 which is imperforate, thereby insuring a maximum effective heat' reflecting surface and retention in the pan of dripped and spilled substances, to facilitate maintenance of the range in a sanitary condition.

It is desirable to keep the drip andreflector pan 23 in a polished condition for purposes of sanitation and to maintain the heat reflecting efliciency thereof, and the aforedescribed construction facilitates convenient access to and removal of said reflector pan for cleaning and polishing the same. As best shown in Fig. 2 the heater coil and frame assembly (25, 26, 21, 28, Fig. 1) may be tilted to raise the side opposite to terminal block 38, said assembly being adapted to pivot upon the aforementioned feet 26 and 26 which restupon the horizontal portions 22 and 2|, respectively, of said support members 22 and 2|. When said coil and frame assembly is thus tilted the end portions 21, 28' and 28 of said heater coils engage the peripheral flange 23 of reflector pan 23 intermediate the points thereof which bear on said horizontal portions 2|. and 22, thus depressing that side of pan 23 and causing the opposite side thereof to rise and present itself above the surface of the range top for convenient grasping and removal of the same. v v

Fig. 6 illustrates a modified form' of support for theheater unit and'reflector pan. The range top I! in this form of the device is preferably made of stainless steel, since a protective ring or rim is not ordinarily used. The wall of the circular openings I6 is preferably provided with flange l6! bent downwardly at substantially a right angle to the plane of top plate IS. The support members 2| and 22 have their opposite flanged ends rigidly secured to the inner surface of the flange |6' and/or to the inner horizontal surface of range ter upon heating thereof, whereby buckling top l5 as by welding, in the manner shown in of said element relatively to said frame is preconnection with flanged end 2! or member 2| vented, and said inner side walls of said notches in Fig. 6. Members 24 are attached to the vertiacting to restrain the coils against substantial cal portions of the support members in the manupward displacement. ner aforedescribed. 2. The combination with a range top having a Fig. '1 illustrates a modification of the arrangesubstantially c c l open n for ed here n. of ment shown in Fig. 5 wherein the arm 25 of an electric heating unit arranged within said frame element 25 is provided witlihotches 38, opening and comprisin a tubular heating eeach of which has a substantially vertical outer l0 ment arranged in Spiral 6011 form, e s 0 side wall and an inner side wall which is'curved prising a ring associated with the rim of said outwardly with respect to the center of the frame Opening a g d w t e Outer S ace of adjacent to the open end of said notch, to prosaid ra t p to upp t the ils f sa d l vide a sort of hook formation on the latter, which ment in p relation d w the pp hook formation is the reverse of that described faces thereof in a common Plane Slightly above in connection with Figs. 1 to 5. With the ars id range t p. sa d h a element having t rrangement shown in Fig. '7 the heater coils are minal por ions provided with wirin terminal normally engaged with th inner curved side members for connection to a source of energy wallsof notches 38 but are free to expand outsupply, said terminal portions being t nd d wardly to a substantial degree within said notches laterally from one Side Of Said unit beyond e upon heating thereof while in use, without danger periphery of Said p by a d Wiring of buckling or distortion of the coils by lateral terminal members are d p s d eath said restraint thereof by the outer walls of the notches, range tap for protection against spillage and the the curved inner walls of the notches acting to like, and means associated h s d i o p orestrain the coils against substantial upward 2 e for bod ly tilting of said heating element displacement, v upwardly at spaced fulcrum points adjacent to The aforedescribed concentric arrangement of the inner periphery 0f a d ri gthe outer and inner sets of spirally wound heater In an electric range tcp heating t, in coils 21 and 28 is particularly advantageous in combination, a metal sheathed heating element respect of the flexibility of heat control which is 30 arranged in Spiral 6011 form, metal ring thus afiorded. For example, the two sets of coils rounding Said elementand having an Outer may be o t d i multiple to provide maxi peripheral portion adapted to overlie the range mum heat, or in series to provide minimum heat, meflns o i ted with Said ring to support or either of said sets may be connected individuthe coils of said element in predetermined spaced ally to provide intermediate heat, the outer set relation and with upper surfaces thereof of coils being connected as for heating large in a common Plane sllghtly above i ring, an t n il such as fry pans and the inner set f imperforate metal reflector pan carried by said 11 being connected as f heating Small supporting means beneath said heating element, t il such as sauce pans. Furthermore, the said heating element having terminal portions sets of heater coils may be made unlike in wattprovided with wiring terminal members 9 6011 age, and additional flexibility is afforded by connecuon to a Source of energy Supply, Sald necting the sets of coils individually or in various portions being extendfiid laterally from one combinations to a three wire supply source. Thus Side of said unit between Bald pan and said ring in a three wire system the maximum heat would and beyPnd the latter wherebY 9? assembly of be pmvided by connecting the two heating 4 said unit with a range top said wiring terminal merits in parallel across the 220 volt lines of the members are adapted to be dlsposedbeneath said source of supply. The minimum heat would be range provided by connecting the two heating elements with. range top having in series across the 110 volt lines. Various other substantliuy circular opfmmg formed t t of combinations in which the heating elements may an heating arranged wlthm Said be connected to the Source of supply will opening and comprising a metal sheathed tubular parent to those skilled in the art. heating element arranged in spiral coil form, What I claim as new and desire to secure by means comprising a ring associated with the rim Letters Patent of said opening and engaged with the outer sur- 1 In an electric range top heating unit in face of said range'top to support the coils of said combination, a spirally formed metal sheathed g elemelt m g f relation Y heating element, a stamped sheet metal frame zf fg e n 321 g? p comprising amultiplicity of rigidly united radially 51g y range Sal Hg 9 disposed arms arranged vertically on edge, each m havmg downwardly offset terminal porof said arms having a multiplicity of spacedi an insulating terminal block f i a vernotches formed in the upper edge thereof, the an *3: horizon?! wall s 5 ternot hes in Said arms hem .ointl ada d o mina mem rs arrange upon sai ver ical wall Q g 3 y pte t re on the side opposite to said heating unit and beceive the coilsof said heating element and to Support the same with the upper Surfaces thereof neath said horizontal wall, whereby said terminal in a common plane slightly above the upper edges members. are ljrotected. agamst spillage and the of the respective arms, the outer sidewall of each mm the terminal Portlons of s id heating elenotch being substantially vertical and the inner .ment being extended laterally from one side of side wall of each notch being of laterally concave said unit beyond the Periphery of said opening f r t normauy accommodate the correspond and being adapted to penetrate the vertical wall ngly Shaped transverse Contour of said heating of said block for mechanical and electrical secureelement in paced relation to said outer side wall ment to said terminal members to further protect i outer id walls of said notches providing a the latter against spillage and the like, said terpredetermined degree of lateral outward clear- 11111191 members Providing for o c on of said ance for the adjacent portions of said eleheating element to a source of energy supply.

ment as an incident to expansion oi the lat- The combination w a range we aving a substantially circular opening formed therein, oi an electric heating unit arranged within said opening and comprising a metal sheathed tubular heating element arranged in spiral coil form, means comprising a ring associated with the rim of said opening and engaged with the outer surface of said range top to support the coils of said element in fixed spaced relation with the upper surfaces thereof in a common plane slightly above said range top, said means also comprising a pair of sheet metal support members extending fiatwise diametrically across said opening at substantially right angles to each other, a coil supporting frame having four arms adapted to engage said support members, respectively, said heating element having downwardly oflset terminal portions, said terminal portions being provided at their ends with wiring terminal members for connection of said heating element to a source of energy supply and being extended laterally beyond the periphery of said opening whereby said terminal members are disposed beneath said range top, an imperforate reflector pan carried by said support members inwardly of the outer ends of the arms of said coil supporting frame, said frame being tiitable upwardly and adapted to be fuicrumed at the ends of two of its arms upon said support members, and said pan being adapted upon upward tilting of said frame to be engaged at its adjacent peripheral edge portion by said downwardly oilset terminal portions, whereby the diametrically opposite edge portion of said pan is simultaneously tilted upwardly and presented above said range top for free and unobstructed removal from beneath said 7 frame upon a further slight degree of manual upward tilting of said pan independently of said frame.

EDWIN N. LIGHTFOOT. 

